Optical Signal Distribution Assembly With Optical Connector Holder

ABSTRACT

A connector holder ( 22 ) suitable for use in a communications signal distribution system, comprising first and second parts between which an optical connector element may be secured, and which have means for locating the holder ( 22 ) in one of a number of different positions and/or orientations on a base or other support of an optical fibre termination unit, whereby to permit a selected one of a number of different connector elements to be held between the two parts of the connector holder, and means for holding the two parts together with a connector element between them.

The present invention relates to a signal distribution assembly, andparticularly (although not exclusively) to an interface assemblysuitable for domestic applications, and to a connector for usetherewith.

The increasing use of optical fibres for the transmission of signalinformation in urban environments, it is becoming more common to deliverinformation signals to households on optical fibres. Thus, instead ofcopper wire cables connected to domestic establishments it is nowpossible to bring optical fibres directly into the home. This makesbroadband signals available economically and allows a wide range ofdifferent information to be transmitted simultaneously on a single line.At the termination within the domestic establishment a number ofdifferent connectors are required for the different signal-utilisingelectrical equipment items which may be in use in the home. For example,the incoming signals on a single optical fibre may be delivered to atelephone, a computer, a facsimile machine, a television or otherelectrical signal-utilising equipment. Each of these items, hereinafterreferred to generically as consumer units, requires a separateelectrical signal line input, and in order to separate the multiplicityof signals carried on the optical fibre it is necessary to install anelectronic interface unit having a transducer for converting the opticalsignals into electrical signals, and an electronic circuit forseparating out the individual signals intended for different consumerunits and delivering them to appropriate sockets to receive connectorelements electrically connected to the individual consumer units byelectrically conductive wire.

The formation of an optical coupling at the termination of an opticalfibre requires accurate positioning of the elements in order to ensurethat the optical coupling functions correctly. For this reason it hasconventionally been necessary, once an optical fibre has been broughtinto a domestic environment, for the cable installer to leave in place afibre termination unit which comprises an optical splice and a so-called“pigtail” which comprises an excess length of optical fibre wound in acasing and running between the incoming optical fibre, to which it isconnected by a suitable splice. The need for the excess length ofoptical fibre results from the fact that splicing of optical fibres tochange connections usually involves cutting the fibre and, thereforeshortening its length. The excess length is necessary in order to ensurethat any future changes to the configuration of the installation cantake place bearing in mind that optical fibre has a minimum bend radiusbeyond which the fibre must not be bent since this would result in adegradation of the transmitted signal, thereby losing the benefits ofutilising optical fibres in the first place.

According to one aspect of the present invention an alternativeconfiguration is provided in which the fibre termination unit installedby the cable supplier can be fitted with an optical fibre connector heldin a universal connector holder which is adapted to be able to receiveany one of a wide range of known commercially available connectorelements. The particular connector element in use in any area isdetermined inter alia by the Local Authority or commercialconsiderations, and because a wide range of electrical connectors isavailable on the market it is known that different connector elementswill be utilised in different areas. A national company acquiring fibretermination units from a single source will, however, wish to be able toinstall those units anywhere in the country regardless of the particularchoice made by the Local Authority of individual optical connectorelements to be utilised in their area. The present invention seeks toprovide means by which this can be achieved.

In another aspect of the present invention there are provided means bywhich an electronic interface unit of standardised dimensions can befitted directly by a user with a single, simple plug-in action withoutrequiring any specialist skill to make the optical connection betweenthe connector element terminating the optical fibre pigtail in the fibretermination unit with a connector linking to a transducer for convertingthe optical signals into electrical signals. The present invention thuscomprehends a signal distribution assembly comprising a fibre interfaceunit having a connector element in a fixed location capable of receivingan electronic interface unit located by suitable guide means to adopt anaccurate relative position and orientation with respect to the fibretermination unit without requiring specialist operatives to make theoptical connection between the two units.

At the heart of this system is a universal optical fibre connectorholder suitable for use in a fibre optic communications signaldistribution system comprising first and second parts between which anoptical connector element may be secured, and which have means forlocating one part of the holder in one of a plurality of differentpositions and/or orientations on a base of an optical fibre terminationunit whereby to permit a selected one of a number of different connectorelements to be held between the two parts of the connector holder andmeans for holding the two parts together with a connector elementbetween them.

As used in this specification the term “base” will be understood torefer to any form of support for the components of a fibre terminationunit, and to include within its scope a flat panel or tray which may beopen, or an enclosed casing or housing (in which case the “base” may beone wall of the casing or housing).

A connector holder as defined hereinabove may be orientable intodifferent orientations to hold different connectors in the samepredetermined position, the connectors being selectable from at leastMT-RJ, SC, SC duplex, LC MU and Lcμ types, and possibly also othercommercially available connector elements.

The present invention also comprehends a fibre termination unitcomprising a base (as herein defined) having a port for receiving anincoming optical fibre, means for storing an excess length of opticalfibre, and an optical fibre connector located at the free end of theoptical fibre for making an optical connection with a complementingcooperating connector of an interface unit having a transducer forconverting the optical signals carried by the optical fibre intoelectrical signals, the said optical fibre connector being retained in aholder having means by which it can be secured to a base or casing ofthe fibre termination unit in a selected position and/or orientationwhereby to locate a selected said connector in a predetermined positionand/or orientation for connection to an interface unit having acomplementary cooperating connector.

A fibre termination unit formed as an embodiment of the presentinvention may have one of the base and the connector holder providedwith a plurality of projections, the other having a plurality ofopenings, the said projections and openings being so positioned that theconnector holder can engaged onto the base in one of a plurality ofdifferent predetermined positions and/or orientations.

Thus, the base of the fibre termination unit may be provided with meansfor receiving and locating any one of a number of different holders,each adapted to hold a specific connector, or may receive a single typeof holder in different positions and/or orientations, the single holderbeing adapted to receive a range of different connectors.

In a preferred embodiment of the invention the base of the fibretermination unit carries or is formed with guide means by which anelectronic interface unit can be located and guided into position withthe optical connector element making connection with the opticalconnector element on the fibre termination unit.

The said guide means of the fibre termination unit may comprise elongateguide members installable or pre-installed to project from the unit in adirection parallel to the direction of relative approach of theconnector elements when they are introduced into a coupling orconnection relationship. The guide members (preferably pins) mayconveniently be provided together with the electronic interface unit forinstallation by the customer in appropriate formations (preferablyapertures) of either one of the respective units prior to bringing theunits together.

The base of the fibre termination unit may be provided withsnap-engagement elements for engagement with cooperating elements of anelectronic interface unit whereby to hold the two said units together.This physical interconnection of the two units preferably also relievesthe pressure on the connector elements, holding them in position bymeans additional to any snap-engagement means by which the connectorelements are secured together.

In a fibre termination unit formed as a preferred embodiment of theinvention the connector elements have snap-engagement components toretain them together in coupled relationship, and the connector holderis so positioned that upon connection of the interface unit with thefibre termination unit the snap-engagement of the connector elementsoccurs before the snap-engagement of the casings or housings of theinterface unit and the fibre termination unit.

The present invention also comprehends a signal distribution assembly ofa communication system comprising a fibre termination unit and anelectronic interface unit, in which the fibre termination unit and theelectronic interface unit each have cooperating optical fibre connectorelements, and casing guide and location elements allowing an electronicinterface unit to be connected to a previously-installed fibretermination unit in a single connection operation, the guide elementsbeing such as to locate and align the connector elements in anorientation such as to make on optical connection between the opticalconnector elements upon fitting together the said two units guided bythe guide elements, the assembly preferably further comprising any ofthe features hereinbefore described. Preferred among such furtherfeatures are:—

-   -   either the said optical fibre connector element of the fibre        termination unit is retained in a holder having means by which        it can be secured to a base or casing of the fibre termination        unit in a selected position and/or orientation whereby to locate        a selected said connector, selected from a group comprising two        or more different connectors, in a predetermined position and/or        orientation for connection to the said interface unit;    -   or the said guide elements comprise elongate members (preferably        pins) installable or pre-installed to project from either one of        the said units in a direction parallel to the direction of        approach of the connector elements when being introduced into        coupling connection relationship;    -   or the said units are provided with snap-engagement elements for        engagement with cooperating elements of each other to hold the        two said units together, and the connector elements have        snap-engagement elements to retain them together in coupled        relationship and are so positioned that upon connection of the        interface unit with the fibre termination unit the        snap-engagement of the connector elements occurs before the        snap-engagement of the fibre termination unit and the interface        unit.

A signal distribution assembly formed as an embodiment of the inventionmay further be provided with electrical connectors in the interface unitto form electrical connections with different electrical signal consumerunits such as telephone, facsimile machine, television, computer and thelike, typically RJ45 connectors may be used. In some preferredembodiments of the assembly or fibre termination unit according to thepresent invention, the fibre termination unit incorporates a televisionreceiver, for example a CATV receiver, and connection means forconnecting the receiver to a television display unit. In suchembodiments, the fibre termination unit may have a service/customerdemarcation cover with an aperture providing access to connection meansfor connecting television signal and power cables to the receiver.

Various embodiments of the present invention will now be moreparticularly described, by way of example, with reference to theaccompanying drawings, in which:

FIG. 1 is a plan view from above of a fibre termination unit formingpart of the signal distribution assembly of the present invention;

FIG. 2 is a perspective view from above of an interface unit suitablefor use with the present invention to form a combined signaldistribution assembly;

FIG. 3 is a plan view from above of the two units of FIGS. 1 and 2 showninterconnected to form a signal distribution assembly, shown with theircovers removed to expose the internal components;

FIG. 4 is an enlarged view of the fibre termination L×nit illustrating adifferent form of optical connector, and illustrating the universaloptical connector holder in a different position;

FIG. 5 illustrates a perspective view of the universal optical connectorholder showing a first optical connector in one configuration thereof;

FIG. 6 is a perspective view of the universal optical connector holderof FIG. 5 illustrating it in a different configuration utilising adifferent type of optical connector in which two optical fibreconnectors are mounted in the holder;

FIG. 7 illustrates the universal optical fibre connector holder inexploded view showing the two parts in a first orientation (FIG. 7 a)and a second orientation (FIG. 7 b); and

FIG. 8 shows a fibre termination unit according to the present inventioncarrying a CATV receiver having power and signal cable connectionpoints, with a service/customer demarcation cover of generally knownkind modified by a cut-out aperture providing access for power andsignal (preferably coaxial) cables to be connected to the receiver, asshown.

Referring now to the drawings, and particularly to FIG. 1 thereof, thesignal distribution assembly of the present invention comprises a fibretermination unit generally indicated 11 (FIG. 1) and an interface unitgenerally indicated 12 (FIG. 2) intended to be interconnected to thefibre termination unit to form a composite signal distribution assembly.

In use it is anticipated that the fibre termination unit will beinstalled in a building by the cable installer having brought an opticalfibre 13 into the building, this optical fibre being spliced at a splice14 to a pigtail 15 an overlength of which is stored in a plurality ofcoils on a base 16 of a casing 17 of the fibre termination unit. Thebase 16 has a plurality of spaced projections 18 and guides 19 in ashallow depression which forms a suitable housing for the overlength ofpigtail allowing this to be retained safely and securely with thecurvature of the optical fibres greater than the minimum bend radius. Afree end 20 of the pigtail is connected to a connector element 21 of anoptical fibre connector which is held in a universal optical fibreconnector holder 22. The universal fibre connector holder 22 will bedescribed in more detail below. The base 16 of the lower part of thecasing 17 has a plurality of holes 23 in positions spaced to receive theconnector holder 22 in one of a number of positions or orientationswhich will be described in more detail below. The casing 17 of theinterface unit 11 is in the form of a shallow tray having upstandingside walls 24, 25 and end walls 26, 27 the latter of which has a largeshallow U-shape cut-out portion 28.

Extending parallel to the side walls 24, 25 of the casing 17 and securedin respective housings 29, 30 therein are two parallel metal guide pins31, 32 the function of which will be explained in more detail below.These pins axe threaded at their ends to allow them to be fitted by theend user to prepare the fibre termination unit to receive an interfaceunit. The pins are fitted by inserting them into openings in the casingof the fibre termination unit and threadedly engaging them on captivenuts provided for the purpose. Opposite the shallow cut-out portion 28in the end wall 26 of the tray 17 are a plurality of generally U-shapenotches or openings 33 the purpose of which will be described in moredetail below.

Referring now to FIG. 2, the interface unit 12 comprises a printedcircuit board 40 of electronic components which are known per se andwill not, therefore, be described in further detail herein except to saythe board 40 carries an optical connector element 41 complementary tothe optical connector element 21 of the fibre termination unit, andintended for connection therewith, this connector incorporating atransducer for converting the optical signals to electrical signalswhich are then filtered and processed by the electronic circuitry toprovide individual output signals on a range of different sockets 42,43, 44 in an end face 45 of a casing generally indicated 46 of theinterface unit housing the printed circuit board 40. This end wall 45also has an opening 47 through which the connector element 21 of thefibre termination unit can project in forming the connection with theconnector element 41.

On each side the casing 46 has two generally cylindrical guide channels48, 49 for receiving the guide pins 31, 32 of the fibre termination unit11 when the interface unit 12 and the fibre termination unit 11 arefitted together.

In practice, because the fibre termination unit will be installed in afixed position by the cable supplier it is anticipated that theinterface unit 12 will be fitted to the fibre termination unit 11 byinserting the guide pins 31, 32 of the interface unit 11 throughopenings 50, 51 in the end wall 45 of the casing 46 of the interfaceunit 12 leading to the cylindrical channels 48, 49 the interior surfaceand/or structure of which is such as to engage these guide pins 31, 32firmly without any play, but not so firmly as to prevent the twocomponents being brought together manually. If the assembly ishorizontally orientated the guide pins may support as well as locate theinterface unit.

The end wall 45 of the interface unit 12 has two resilient projectingteeth 52, 53 which engage through openings 54, 55 in the end wall 27 ofthe tray 17 constituting the base part of the fibre termination unit 11.When the two units are pushed together firmly the resilient teeth 52, 53snap-engage into the openings 54, 55 to hold the two units firmlytogether. By suitably positioning the holes 23 which determine thelocation of the connector holder 22 it is possible to ensure that anysnap-engaging cooperating parts of the two connector elements 21, 41snap-engage together just before the snap-engagement of the teeth 52, 53in the holes 54, 55 so that, as the two parts are fitted together, theuser can hear a first sharp click to confirm that the optical connectionhas been made and then a second click as the two components are fittedtogether.

As can be seen in FIG. 3, which shows the fibre termination unit 11securely connected to an interface unit 12, an intermediate cover 60 isprovided over the pigtail overlength storage cavity in the tray 17 toprotect the spare length of pigtail 15 from abrasion by wires which canthen be led through the openings 33 in the end wall 26 of the fibretermination unit 11, across the tray 60 to be plugged into theconnectors 42, 43 or 44 as appropriate, depending on the nature of theelectrical consumer unit to which the wires are connected.

FIG. 4 illustrates a fibre termination unit similar to that of FIG. 1,but in which the universal connector holder 22 is fitted into adifferent set of the openings 23 and carries a different opticalconnector arrangement. In fact, it carries two optical connectors 61, 62to which two pigtails 63, 64 are spliced, and which connect intocooperating connector elements (not shown) within the connector 41 ofthe interface unit.

FIGS. 5 to 7 illustrate the form of the connector holder 22. Thiscomprises a first part 65 shaped to fit together with a second part 66.In the embodiment illustrated the two parts 65, 66 are held together byscrews 67 although other fixing means, such as bolts, snap-engagementparts or the like may be used. The two connector holder parts 65, 66clamp between them a connector element 68. The lower part 65 of theconnector holder has four legs in pairs, one pair 69 at the right handend as viewed in FIG. 5, and the second pair 70 somewhat spaced from theleft hand end as viewed in FIG. 5. The two components 65, 66 of theoptical connector holder 22 have, as can be seen in FIGS. 7 a and 7 b acomplementary shape which allows them to be fitted together in a numberof different ways to form suitably shaped cavities for receivingdifferent connectors such as the MT-RJ, the SC, SC duplex, LC or LCμtype of connector.

As can be seen in FIG. 7 a the lower connector holder part 65 comprisesa plate-like main base 80 downwardly from which project the previouslymentioned legs 69 and 70. Upwardly from the base 80, at each endthereof, are two upstanding blocks 72, 73 each having a channel-shaperecess 74, 75 therein. Upwardly from the blocks 72, 73 project two pairsof legs 76 and 77 which are aligned with but face in opposite directionsfrom the legs 69, 70 which project downwardly from the base plate 80.Although shown as straight legs in FIGS. 7 a and 7 b, the legs 69, 70,and the legs 76, 77 may have laterally projecting teeth at their freeends for snap-engagement in the holes 23 of the base of the fibretermination unit. As can be seen in FIG. 7 b, which shows the plate 80inverted, the opposite face thereof bears two longitudinal channels 78,79 extending the full length of the plate 80.

The upper part 66 of the connector holder 22 is a generally plate-shapebody 81 having four holes 82, one in each corner thereof, which when thetwo parts 66, 65 are fitted together, align with cooperating holes 83 inthe bottom part 65 to receive the screws 67. As can be seen in FIG. 7 aon one face of the plate-like body 81 of the upper part 66 of theconnector holder 22 there are two longitudinal channels 88, 89corresponding in form to the channels 78, 79 in the bottom part 65, andas can be seen in FIG. 7 b on the other face of the plate 81 there arerespective upstanding blocks 84, 85 having shallow channels 86, 87therein matching the channels 74, 75 in the blocks 72, 73 of the bottompart.

This configuration then allows the two parts to be fitted together in anumber of different relative configurations the first of which is shownin FIG. 5 in which the two flat faces of the plate-like bodies 80, 81face one another to form an interior cavity with two aligned channelsdefined by the two cavities 75, 86 at one end and 74, 87 at the other.The connector 68 is thus retained in the cavity defined by the twochannels 74, 87.

Without changing the relative orientation of the upper and lower part ofthe connector holder 22, however, it is also possible to fit twoconnector elements within the laterally transverse channel definedbetween the two parts as shown in FIG. 6. Other configurations can beformed by inverting both the upper and lower parts so that thelongitudinal channels 78, 79 in the lower part and 88, 89 in the upperpart face one another to form suitable longitudinal channels forreceiving a different shape of connector element.

FIG. 8 shows an example of a fibre termination unit according to thepresent invention carrying a CATV receiver having power and signal cableconnection points, with a service/customer demarcation cover modified bya cut-out aperture providing access for power and signal (preferablycoaxial) cables to be connected to the receiver.

1. A signal distribution assembly for a communications system comprisinga fibre termination unit and an electronic interface unit, in which thefibre termination unit and the electronic interface unit each havecooperating optical fibre connector elements, and casing guide andlocation elements allowing the electronic interface unit to be connectedto the previously-installed fibre termination unit in a singleconnection operation, the guide elements being such as to locate andalign the connector elements in an orientation such as to make anoptical connection between the optical connector elements on fittingtogether the two units guided by the guide elements, including one ormore of the following configurations: (a) the said optical fibreconnector element of the fibre termination unit is retained in a holderhaving means by which it can be secured to a base or casing of the fibretermination unit in a selected position and/or orientation whereby tolocate a selected said connector, selected from a group comprising twoor more different connectors, in a predetermined position and/ororientation for connection to the said interface unit; (b) the saidguide elements comprise elongate members installable or pre-installed toproject from either one of the said units in a direction parallel to thedirection of approach of the connector elements when being introducedinto coupling connection relationship; or (c) the said units areprovided with snap-engagement elements for engagement with cooperatingelements of each other to hold the two said units together, and theconnector elements have snap-engagement elements to retain them togetherin coupled relationship and are so positioned that upon connection ofthe interface unit with the fibre termination unit the snap-engagementof the connector elements occurs before the snap-engagement of the fibretermination unit and the interface unit.
 2. A signal distributionassembly as claimed in claim 1, in which there are further providedelectrical connectors in the interface unit to form electricalconnections with different electrical signal consumer units such astelephone, facsimile machine, television, computer and the like.
 3. Asignal distribution assembly as claimed in claim 1, wherein the fibretermination unit incorporates a television receiver and connection meansfor connecting the receiver to a television display unit.
 4. A signaldistribution assembly according to claim 3, wherein the fibretermination unit has a service/customer demarcation cover with anaperture providing access to connection means for connecting televisionsignal and power cables thereto.
 5. A connector holder suitable for usein a communications signal distribution system, comprising first andsecond parts between which an optical connector element may be secured,and which have means for locating the holder in one of a number ofdifferent positions and/or orientations on a base or other support of anoptical fibre termination unit, whereby to permit a selected one of anumber of different connector elements to be held between the two partsof the connector holder, and means for holding the two parts togetherwith a connector element between them.
 6. A connector holder as claimedin claim 5, orientable into different orientations to hold differentconnectors in a given predetermined position and/or orientation forcooperation with a complementary connector.
 7. A connector holder asclaimed in claim 5 or claim 6, in which the said selected connector maybe chosen from MT-RJ, SC, SC duplex, LC, MU and Lcμ types.
 8. A fibretermination unit comprising a base having a port for receiving anincoming optical fibre, means for storing an excess length of opticalfibre, and an optical fibre connector at the free end of the opticalfibre for making an optical connection with a complementary cooperatingconnector of an interface unit having a transducer for converting theoptical signals carried by the optical fibre into electrical signals,the said optical fibre connector being retained in a holder having meansby which it can be secured to a base or casing of the fibre terminationunit in a selected position and/or orientation whereby to locate aselected said connector in a predetermined position and/or orientationfor connection to an interface unit having a complementary cooperatingconnector.
 9. A fibre termination unit as claimed in claim 8, in whichthe holder has means by which it may retain one of two or more differentconnectors selected from a group comprising two or more differentconnectors.
 10. A fibre termination unit as claimed in claim 8, in whichthe holder has means by which it may retain a connector selected from agroup comprising six different connector types.
 11. A fibre terminationunit as claimed in claim 8, in which one of the base or casing of thefibre termination unit and the connector holder is provided with aplurality of projections, the other having a plurality of openings, thesaid projections and openings being so positioned that the connectorholder can be located onto the base in one of a plurality of differentpredetermined positions and/or orientations.
 12. A fibre terminationunit as claimed in claim 8, in which the base or casing of the unitcarries or is formed with guide means by which an electronic interfaceunit can be located and guided into a position in which the opticalconnector element thereon connects with the optical connector element ofthe fibre termination unit.
 13. A fibre termination unit as claimed inclaim 12, in which the said guide means comprise parallel elongate pinsprojecting from the base of the unit in a direction parallel to thedirection of approach of the connector elements when being introducedinto coupling connection relationship.
 14. A fibre termination unit asclaimed in claim 12, in which the base or casing is provided withsnap-engagement elements for engagement with cooperating elements of anelectronic interface unit whereby to hold the two said units together.15. A fibre termination unit as claimed in claim 14, in which theconnector elements have snap-engagement elements to retain them togetherin coupled relationship, and the connector holder is so positioned thatupon connection of the interface unit with the fibre termination unitthe snap-engagement of the connector elements occurs before thesnap-engagement of the base or casing of the fibre termination unit andthe interface unit.
 16. A fibre termination unit as claimed in claim 8,wherein the fibre termination unit incorporates a television receiverand connection means for connecting the receiver to a television displayunit.
 17. A fibre termination unit according to claim 16, wherein thefibre termination unit has a service/customer demarcation cover with anaperture providing access to connection means for connecting televisionsignal and power cables thereto.